Traffic lane guidance system for vehicle and traffic lane guidance method for vehicle

ABSTRACT

A lane guidance system for a vehicle for guiding a vehicle to a recommended lane in which the vehicle is recommended to run out of traffic lanes included in a route from a first point to a second point through the use of an output unit mounted on the vehicle includes: a calculating unit that calculates a predicted value of an occurrence probability of sudden lane change as information indicating the occurrence probability of sudden lane change when the vehicle runs in sections corresponding to a plurality of links; a setting unit that sets the recommended lane on the basis of the predicted value; and a generating unit that generates guidance information for the recommended lane and that outputs the guidance information to the output unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 15/028,196,filed Apr. 8, 2016 (allowed), which is a National Stage entry ofInternational Application No. PCT/IB2014/002282, filed Oct. 8, 2014,which claims priority to Japanese Application No. 2013-211867, filedOct. 9, 2013. The entire disclosures of the prior applications areconsidered part of the disclosure of the accompanying continuationapplication, and are hereby incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a traffic lane guidance system for avehicle and a traffic lane guidance method for a vehicle for guiding avehicle to a traffic lane so as to suppress the occurrence of suddenlane change of a vehicle.

2. Description of Related Art

In a navigation system mounted on a vehicle, guidance of a route from acurrent point as a first point and a destination point as a second pointis carried out using voice, images, or the like. A navigation system forguiding an optical traffic lane for a running vehicle has beendeveloped.

For example, in a driving support system described in Japanese PatentApplication Publication No. 2012-221353 (JP 2012-221353 A), theoccurrence probability of sudden lane change when a vehicle enters apoint of intersection from traffic lanes is calculated as statisticalinformation of right turns and left turns. By guiding a vehicle to atraffic lane in which the vehicle has to run in the vicinity of theintersection on the basis of the calculated statistical information, theoccurrence of sudden lane change when the vehicle enters the point ofintersection is suppressed.

However, in the driving support system described in JP 2012-221353 A,the lane change frequency occurring while a vehicle runs from a point ofintersection to a subsequent point of intersection is not considered atall. Accordingly, when the lane change frequency of a vehicle increasesin a route portion other than the points of intersection in the entireroute from a current point to a destination point by guiding the vehicleto a traffic lane in which the vehicle has to run in the vicinity of thepoints of intersection, the occurrence of sudden lane change of thevehicle in the route portion may be rather promoted. That is, in thedriving support system, an optical traffic lane in the vicinity of apoint of intersection is guided on the basis of local information foreach point of intersection so as to suppress the occurrence of suddenlane change when the vehicle enters the point of intersection.Accordingly, when the entire route from the current point to thedestination point is considered, it cannot be said that the guidedtraffic lane is necessarily an optimal traffic lane for suppressing theoccurrence of sudden lane change of a vehicle.

SUMMARY OF THE INVENTION

The invention provides a traffic lane guidance system for a vehicle anda traffic lane guidance method for a vehicle that can guide a vehicle toa traffic lane and that can suppress the occurrence of sudden lanechange in consideration of the entire route from a first point to asecond point.

According to a first aspect of the invention, there is provided atraffic lane guidance system for a vehicle for guiding a vehicle to arecommended lane in which the vehicle is recommended to run out oftraffic lanes included in a route from a first point to a second pointthrough the use of a guidance information output unit mounted on thevehicle. The traffic lane guidance system for a vehicle includes: apredicted value calculating unit that calculates a predicted value of anoccurrence probability of sudden lane change as information indicatingthe occurrence probability of sudden lane change when the vehicle runsin sections corresponding to a plurality of links, which are set byconnecting a plurality of nodes corresponding to traffic lanes in atraveling direction of the vehicle and a direction intersecting thetraveling direction of the vehicle, for each of the plurality of linkson the basis of statistical information acquired from a plurality ofvehicles and an information quantity of the statistical information; arecommended lane setting unit that sets the recommended lane on thebasis of the predicted value calculated by the predicted valuecalculating unit; and a guidance information generating unit thatgenerates guidance information for the recommended lane set by therecommended lane setting unit and that outputs the generated guidanceinformation to the guidance information output unit.

According to a second aspect of the invention, there is provided atraffic lane guidance method for a vehicle of guiding a vehicle to arecommended lane in which the vehicle is recommended to run out oftraffic lanes included in a route from a first point to a second pointthrough the use of a guidance information output unit mounted on thevehicle. The traffic lane guidance system for a vehicle including:calculating a predicted value of an occurrence probability of suddenlane change as information indicating the occurrence probability ofsudden lane change when the vehicle runs in sections corresponding to aplurality of links, which are set by connecting a plurality of nodescorresponding to traffic lanes in a traveling direction of the vehicleand a direction intersecting the traveling direction of the vehicle, foreach of the plurality of links on the basis of statistical informationacquired from a plurality of vehicles and an information quantity of thestatistical information; setting the recommended lane on the basis ofthe calculated predicted value of the occurrence probability of suddenlane change; and generating guidance information for the set recommendedlane and that outputs the generated guidance information to the guidanceinformation output unit.

According to these configurations, the predicted value calculating unitcalculates the predicted value of the occurrence probability of suddenlane change when the vehicle runs in the route from the first point tothe second point for each section corresponding to the links. Therecommended lane setting unit extracts the route in which the suddenlane change of the vehicle does not occur well from the route from thefirst point to the second point on the basis of the calculated predictedvalues and sets the traffic lane included in the extracted route as therecommended lane. That is, the recommended lane is set to a traffic lanein which the occurrence of the sudden lane change of the vehicle can besuppressed in consideration of the entire route from the first point tothe second point. Accordingly, by causing the guidance informationgenerating unit to generate guidance information for the set recommendedlane and to output the generated guidance information to the guidanceinformation output unit, it is possible to guide the vehicle to atraffic lane more suitable for suppressing the occurrence of the suddenlane change of the vehicle.

In the aspect, the recommended lane setting unit may set the trafficlane included in the route in which the total sum of the predictedvalues of the occurrence probability of sudden lane change is minimizedin the route from the first point to the second point.

According to this configuration, the traffic lane included in the routein which the sudden lane change of the vehicle occurs less inconsideration of the entire route from the first point to the secondpoint is set as the recommended lane.

In the aspect, the recommended lane setting unit may set the trafficlane included in the route in which the total sum of the predictedvalues of the occurrence probability of sudden lane change is minimizedunder the condition not including the link in which the predicted valueis greater than a predetermined threshold value in the route from thefirst point to the second point as the recommended lane.

According to this configuration, the route locally including a sectionin which the sudden lane change of the vehicle often occurs in the routefrom the first point to the second point is excluded from appropriateroute candidates. That is, since the recommended lane does not locallyinclude a section in which the sudden lane change of the vehicle oftenoccurs, it is possible to guide the vehicle to a traffic lane moresuitable for suppressing the occurrence of the sudden lane change of thevehicle.

In the aspect, the recommended lane setting unit may determine thetraffic lane included in the route in which the total sum of thepredicted values of the occurrence probability of sudden lane change isminimized by applying a Dijkstra's algorithm to the predicted value ofthe occurrence probability of sudden lane change calculated for eachlink included in the route from the first point to the second point.

According to this configuration, it is possible to easily implement aconfiguration for determining the route in which the total sum of thepredicted values of the occurrence probability of sudden lane change isminimized in the route from the first point to the second point.

In the aspect, the recommended lane setting unit may set the trafficlane included in the route in which the number of links set byconnecting the plurality of nodes in the direction intersecting thetraveling direction of the vehicle is minimized under the condition notincluding the link in which the predicted value is greater than apredetermined threshold value in the route from the first point to thesecond point as the recommended lane.

According to this configuration, on the premise that the route does notlocally include a section in which the sudden lane change of the vehicleoften occurs, a traffic lane included in the route in which the lanechange frequency is minimized in the route from the first point to thesecond point is set as the recommended lane. That is, since therecommended lane does not locally include a section in which the suddenlane change of the vehicle often occurs and the lane change frequency isminimized, it is possible to guide the vehicle to a traffic lane evenmore suitable for suppressing the occurrence of the sudden lane changeof the vehicle.

In the aspect, the predicted value calculating unit may set an additionvalue, which is added to the predicted values of the occurrenceprobability of sudden lane change in the links set by connecting theplurality of nodes in the direction intersecting the traveling directionof the vehicle, to be greater than an addition value added to thepredicted values in the links set by connecting the plurality of nodesin the traveling direction of the vehicle, and the recommended lanesetting unit may set the recommended lane on the basis of the predictedvalues of the occurrence probability of sudden lane change to which theaddition value is added.

In general, when a vehicle changes a traffic lane, a driver's burdenwhen the sudden lane change of the vehicle occurs is greater than thatwhen the vehicle runs straightly in a lane. Accordingly, in theabove-mentioned configuration, the weighting value of the addition valuefor the predicted value of the occurrence probability of sudden lanechange in a link corresponding to the section in which the vehicle runsat the time of changing the traffic lane is set to be greater than thatfor the predicted value in a link corresponding to a section in whichthe vehicle runs straightly in a lane. That is, the weighting value isset for the predicted values of the occurrence probability of suddenlane change depending on situations in consideration of the variation ofthe driver's burden when the sudden lane change occurs depending onwhether to change the lane. Accordingly, it is possible to guide thevehicle to a traffic lane more suitable for suppressing the occurrenceof the sudden lane change of the vehicle depending on the situations.

In the aspect, the predicted value calculating unit may be able to set aweighting value for the addition value and may gradually increase theweighting value set for the addition value as the distance from a point,at which the steering operation frequency of the vehicle is greater thana predetermined threshold value, decreases in the route from the firstpoint to the second point.

In general, when a vehicle runs in the vicinity of a point at which asteering operation is frequently required such as a point ofintersection, the driver's burden when the sudden lane change occurs atthe time of changing the traffic lane is greater than that when thevehicle runs at other points. Accordingly, in the above-mentionedconfiguration, as the running position of the vehicle becomes closer tothe point, the weighting value for the predicted value of the occurrenceprobability of sudden lane change in the link corresponding to thesection in which the vehicle runs at the time of changing the trafficlane is set to be greater. That is, the weighting value for thepredicted value of the occurrence probability of sudden lane change ischanged depending on the situations in consideration of the variation ofthe driver's burden when sudden lane change occurs due to the variationin the distance from the point. Accordingly, it is possible to guide thevehicle to a traffic lane more suitable for suppressing the occurrenceof the sudden lane change of the vehicle at a point of intersection orthe like depending on the situation.

In the aspect, the predicted value calculating unit may determine asecond addition value which is different from a first addition value asthe addition value to be added to the predicted values of the occurrenceprobability of sudden lane change when the addition value is the firstaddition value and may set the second addition value, when theappropriateness of personal driving characteristics for sectionscorresponding to the links is relatively high, to be smaller than thatwhen the appropriateness is relatively low, and the recommended lanesetting unit may set the recommended lane on the basis of the predictedvalues of the occurrence probability of sudden lane change to which thefirst addition value and the second addition value are added.

In general, when the appropriateness of personal driving characteristicsfor a section corresponding to a link is relatively high, the driver'sburden at the time of changing the traffic lane when the vehicle runs inthe section is smaller than that when the appropriateness is relativelylow. Accordingly, in the above-mentioned configuration, the weightingvalue for the predicted value of the occurrence probability of suddenlane change is changed depending on the situations in consideration ofthe variation of the driver's burden when the sudden lane change occursdue to the appropriateness of the personal driving characteristics forthe section corresponding to the link. Accordingly, it is possible toguide the vehicle to a traffic lane more suitable for suppressing theoccurrence of the sudden lane change of the vehicle depending onpersonal driving characteristics.

In the aspect, the predicted value calculating unit may classifyinformation acquired from the plurality of vehicles as information ofelements of personal driving characteristics into a plurality of drivingcharacteristic information groups, may classify information of elementsof lane characteristics into a plurality of lane characteristicinformation groups, and may set the second addition value to be added tothe predicted values of the occurrence probability of sudden lanechange, when the appropriateness of the driving characteristicinformation groups and the lane characteristic information groups isrelatively high, to be smaller than that when the appropriateness isrelatively low.

According to this configuration, the information of the elements ofpersonal driving characteristics and the information of the elements ofthe traffic lane characteristics are statistically processed andclassified and the weighting value for the predicted value of theoccurrence probability of sudden lane change is changed depending on theappropriateness of the classified information groups. Accordingly, it ispossible to implement the configuration for changing the weighting valuefor the predicted value of the occurrence probability of sudden lanechange depending on the situation in consideration of the variation ofthe driver's burden when the sudden lane change occurs due to theappropriateness of the personal driving characteristics for the sectioncorresponding to the link.

In the aspect, the predicted value calculating unit may determine athird addition value which is different from the first addition valueand the second addition value as the addition value to be added to thepredicted values of the occurrence probability of sudden lane change andmay set the third addition value, when the appropriateness of vehiclecharacteristics for sections corresponding to the links is relativelyhigh, to be smaller than that when the appropriateness is relativelylow, and the recommended lane setting unit may set the recommended laneon the basis of the predicted values of the occurrence probability ofsudden lane change to which the first addition value, the secondaddition value, and the third addition value are added.

In general, when the appropriateness of the vehicle characteristics fora section corresponding to a link is relatively high, the driver'sburden when the sudden lane change of the vehicle occurs at the time ofrunning in the section is smaller than that when the appropriateness isrelatively low. Accordingly, in the above-mentioned configuration, theweighting value for the predicted value of the occurrence probability ofsudden lane change changes depending on the situations in considerationof the variation of the driver's burden when the sudden lane changeoccurs due to the appropriateness of the vehicle characteristics for thesection corresponding to the link. Accordingly, it is possible to guidethe vehicle to a traffic lane more suitable for suppressing theoccurrence of the sudden lane change of the vehicle depending on thesituation.

In the aspect, the positions of the nodes may include a plurality ofpositions spaced in the traveling direction of the vehicle in thetraffic lanes of the route portion between neighboring points ofintersection in the route from the first point to the second point.

According to this configuration, since more nodes than the nodes whenthe nodes are set at only the positions corresponding to the points ofintersection on the route are set on the route, it is possible to betterguide the vehicle to a traffic lane more suitable for suppressing theoccurrence of the sudden lane change of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the invention will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is a block diagram of a traffic lane guidance system for avehicle according to a first embodiment of the invention;

FIG. 2 is a diagram schematically illustrating map information used forthe traffic lane guidance system for a vehicle according to the firstembodiment to set a recommended lane;

FIG. 3 is a graph illustrating a correlation between a prediction valueof an occurrence probability of sudden lane change and an informationquantity of statistical information;

FIG. 4 is a graph illustrating a correlation between a correctioncoefficient and a distance from a point of intersection;

FIG. 5 is a flowchart illustrating schematically illustrating a processflow of a recommended lane guiding process that is performed by thetraffic lane guidance system for a vehicle according to the firstembodiment;

FIG. 6 is a schematic diagram illustrating an example of a recommendedlane set by the traffic lane guidance system for a vehicle according tothe first embodiment; and

FIG. 7 is a schematic diagram illustrating an example of a recommendedlane set by a traffic lane guidance system for a vehicle according to asecond embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS First Embodiment

Hereinafter, a first embodiment of a traffic lane guidance system for avehicle and a traffic lane guidance method for a vehicle will bedescribed with reference to the accompanying drawings.

As illustrated in FIG. 1, the traffic lane guidance system for a vehicleaccording to this embodiment includes an onboard system 101 mounted on avehicle 100 and a control center 200 constituting a probe informationcommunication system. The control center 200 collects and managesvehicle information (probe information) of the vehicle 100 that runs ona road.

The onboard system 101 includes an accelerator sensor 110, a brakesensor 111, a steering angle sensor 112, a yaw rate sensor 113, anacceleration sensor 114, and a vehicle speed sensor 115 as elements foracquiring information on the state of the vehicle 100. These elementsare electrically connected to an onboard controller 150.

The accelerator sensor 110 detects an accelerator pressure varying witha driver's operation of an accelerator pedal and outputs a signalcorresponding to the detected accelerator pressure to the onboardcontroller 150. The brake sensor 111 detects a driver's operation of abrake pedal and outputs a signal corresponding to the detected operationto the onboard controller 150. The steering angle sensor 112 detects asteering angle of a steering wheel on the basis of a variation in thesteering angle of the steering wheel and outputs a signal correspondingto the detected steering angle to the onboard controller 150. The yawrate sensor 113 detects a yaw rate that is a variation rate of arotation angle in the turning direction of the vehicle 100 and outputs asignal corresponding to the detected yaw rate to the onboard controller150. The acceleration sensor 114 detects the acceleration of the vehicleand outputs a signal corresponding to the detected acceleration to theonboard controller 150. The vehicle speed sensor 115 detects a vehiclespeed that is the speed of the vehicle and outputs a signalcorresponding to the detected vehicle speed to the onboard controller150.

The onboard system 101 includes an onboard camera 120, a millimeter-waveradar 121, a global positioning system (GPS) 122, and an onboardcommunication instrument 123 as elements for acquiring information oncircumstances around the vehicle. These elements are electricallyconnected to the onboard controller 150.

The onboard camera 120 takes an image of a predetermined range in frontof the vehicle 100 using an optical CCD (Charge-Coupled Device) camerainstalled in the back of a room mirror or the like. The onboard camera120 outputs an image signal based on the captured image to the onboardcontroller 150.

The millimeter-wave radar 121 has a distance measuring function ofmeasuring a distance between an object present around the vehicle andthe vehicle 100. When an object present around the vehicle is detected,the millimeter-wave radar 121 outputs a signal indicating the detectionresult to the onboard controller 150.

The GPS 122 receives GPS satellite signals for detecting the absoluteposition of the vehicle 100 on which the GPS 122 is mounted. The GPS 122specifies the position of the vehicle 100 on the basis of the receivedGPS satellite signals and outputs longitude and latitude informationindicating the specified position to the onboard controller 150.

The onboard communication instrument 123 acquires information indicatingrunning speeds or longitude and latitude information of other vehicles,for example, by vehicle-vehicle communications with other vehiclespresent around the vehicle 100 and outputs the acquired information tothe onboard controller 150. The onboard communication instrument 123acquires infrastructure information by road-vehicle communications withan optical beacon road machine B (see FIG. 2) and outputs the acquiredinfrastructure information to the onboard controller 150. Theinfrastructure information includes, for example, information on legalrestrictions (such as inhibition of lane change or exclusive lane) intraffic lanes entering a point of intersection.

Map information registered in a map information database 130 includesinformation indicating curves, points of intersection, one-way roads,temporary stop positions, crossings, traffic lights, and longitude andlatitude of facilities. The map information also includes, for example,information indicating that a type of a traffic light is an arrow typetraffic light.

The onboard system 101 includes a navigation system 131 that performsroute guidance of the vehicle 100. The navigation system 131 acquires acurrent point of the vehicle 100 from the onboard controller 150 towhich the detection result of the GPS 122 is input. The navigationsystem 131 searches for a traveling route from the current point (firstpoint) to a destination point (second point) of the vehicle 100 withreference to the map information database 130 using a Dijkstra'salgorithm or the like and outputs the searched traveling route to theonboard controller 150.

The onboard controller 150 of this embodiment includes a section settingunit 151, a vehicle characteristic storage unit 152, a drivingcharacteristic storage unit 153, and a guidance information generatingunit 154. The section setting unit 151 sets the traveling route from thecurrent point to the destination point of the vehicle 100 input from thenavigation system 131 as a traveling section of the vehicle 100.

The vehicle characteristic storage unit 152 stores, for example, theweight of the vehicle 100 or the width of the vehicle 100 ascharacteristic information of the vehicle 100. This information is setin advance as fixed values at the time of initially setting the vehicle100. The vehicle characteristic storage unit 152 may calculate thedriving force of the vehicle 100 and the acceleration of the vehicle 100when the vehicle 100 runs, then may estimate the weight of the vehicle100 as a variable value on the basis of the calculated value, and maystore the estimated value of the weight of the vehicle 100 as thecharacteristic information of the vehicle 100.

The driving characteristic storage unit 153 calculates the runninghistory of the vehicle 100 including the average vehicle speed of thevehicle 100, the average inter-vehicle distance of the vehicle 100, therunning frequency of the left lane in sections in which street parkingfrequently occurs, the occurrence probability of sudden lane change atthe respective running positions of the vehicle 100, and the steeringoperation frequency at the running positions of the vehicle 100 asinformation indicating the driving characteristics of a driver of thevehicle 100.

Specifically, the driving characteristic storage unit 153 calculates thevehicle speed on the basis of the signal input from the vehicle speedsensor 115 and calculates the average vehicle speed of the vehicle 100using the calculated vehicle speed. The driving characteristic storageunit 153 calculates the inter-vehicle distance that is a distancebetween the vehicle 100 and a preceding vehicle on the basis of thesignal input from the millimeter-wave radar 121 and calculates theaverage inter-vehicle distance of the vehicle 100 using the calculatedinter-vehicle distance. The driving characteristic storage unit 153 maycalculate the inter-vehicle distance on the basis of the image signal ofa preceding vehicle imaged with the onboard camera 120 and may calculatethe inter-vehicle distance by vehicle-vehicle communications orroad-vehicle communications of the onboard communication instrument 123.

The driving characteristic storage unit 153 specifies a traffic lane inwhich the vehicle 100 runs on the basis of the image signal of a laneboundary imaged with the onboard camera 120. The driving characteristicstorage unit 153 may receive the image signal of the vehicle 100 imagedwith a camera installed in the optical beacon road machine B by theroad-vehicle communications of the onboard communication instrument 123and may specify the lane in which the vehicle 100 runs on the basis ofthe received image signal. The driving characteristic storage unit 153specifies a section in which street parking frequently occurs on thebasis of the signal transmitted from the control center 200 to theonboard communication instrument 123 via the optical beacon road machineB. The driving characteristic storage unit 153 calculates the frequencyin which the vehicle 100 runs in the left lane in the specified section.

The driving characteristic storage unit 153 determines that the suddenlane change of the vehicle 100 occurs when the variation in the detectedvalue of the steering angle of the steering wheel input from thesteering angle sensor 112 is greater than a predetermined thresholdvalue. The driving characteristic storage unit 153 may determine thatthe sudden lane change of the vehicle 100 occurs when the detected valueof the yaw rate of the vehicle 100 input from the yaw rate sensor 113 isgreater than a predetermined threshold value. The driving characteristicstorage unit 153 may determine that the sudden lane change of thevehicle 100 occurs when the transverse acceleration of the vehicle 100input from the acceleration sensor 114 is greater than a predeterminedthreshold value. The driving characteristic storage unit 153 may receivethe image signal of the vehicle imaged with the camera installed in theoptical beacon road machine B by the road-vehicle communications of theonboard communication instrument 123 and may determine whether thesudden lane change of the vehicle 100 occurs. The driving characteristicstorage unit 153 determines whether the sudden lane change of thevehicle occurs for each traffic lane. The driving characteristic storageunit 153 stores the determination result of whether the sudden lanechange of the vehicle 100 occurs in correlation with the positionacquired from the GPS 122 as the running position of the vehicle 100 atthe time of the determination.

The driving characteristic storage unit 153 calculates the steeringoperation frequency at the respective running positions of the vehicle100 by storing the detection result of the steering operation based onthe signal input from the steering angle sensor 112 in correlation withthe position acquired from the GPS 122 as the running position of thevehicle 100 at the time of the detection. The driving characteristicstorage unit 153 may detect the steering operation on the basis of thedetected value of the yaw rate of the vehicle 100 input from the yawrate sensor 113. The driving characteristic storage unit 153 maydetermine the steering operation on the basis of the detected value ofthe transverse acceleration of the vehicle 100 input from theacceleration sensor 114. The driving characteristic storage unit 153 maydetect the steering operation by analyzing an image captured with theonboard camera 120 and calculating movement in the transverse directionrelative to a preceding vehicle.

The guidance information generating unit 154 receives information on arecommended lane in which the vehicle 100 has to run in the section setby the section setting unit 151 from the control center 200 via theonboard communication instrument 123. The guidance informationgenerating unit 154 generates guidance information for urging a driverto run in the received recommended lane and outputs the generatedguidance information to a human machine interface (HMI) 132 as theguidance information output unit.

The HMI 132 is constituted, for example, by a speaker, a head-updisplay, a monitor of the navigation system 131, and a meter panel. Whenthe guidance information is input from the guidance informationgenerating unit 154, the HMI 132 rings an alarm for urging the driver torun in the recommended lane by voice via the speaker or displays anwarning on the head-up display.

The control center 200 includes a center controller 210 that controlsvarious units and a center communication instrument 211 and a mapinformation database 212 that are electrically connected to the centercontroller 210.

The control center 200 collects vehicle information of the vehicle 100on which the onboard system 101 is mounted from plural vehicles 100.That is, the vehicle information accumulated by each vehicle 100 istransmitted from the onboard communication instrument 123 to the centercommunication instrument 211 by radio communications and is then inputfrom the center communication instrument 211 to the center controller210. Information is transmitted and received between the onboardcommunication instrument 123 and the center communication instrument 211with a constant time cycle by radio communications. The centercontroller 210 stores the input vehicle information for each vehicle ina vehicle database 220.

The vehicle database 220 includes a section storage unit 221, a vehiclecharacteristic storage unit 222, and a driving characteristic storageunit 223. The section storage unit 221 stores information of the runningsection set by the section setting unit 151 of the vehicle 100 byvehicles on the basis of vehicle IDs included in the informationtransmitted from the vehicles 100. The section storage unit 221 updatesthe stored information of the running sections whenever the informationof the running section is transmitted from the vehicles 100 with aconstant time cycle.

The vehicle characteristic storage unit 222 stores the characteristicinformation of the vehicle 100 stored in the vehicle characteristicstorage unit 152 of the vehicle 100 by vehicles on the basis of thevehicle IDs included in the information transmitted from the vehicles100. When the characteristic information of the vehicle 100 stored inthe vehicle characteristic storage unit 152 of the vehicle 100 is afixed value, the vehicle characteristic storage unit 222 does not updatethe stored information of the vehicle characteristics of the vehicles100 whenever the characteristic information of the vehicle 100 istransmitted from the vehicles 100 with a constant time cycle. On theother hand, when the characteristic information of the vehicle 100stored in the vehicle characteristic storage unit 152 of the vehicle 100is a variable value, the vehicle characteristic storage unit 222 updatesthe stored characteristic information of the vehicles 100 whenever thecharacteristic information of the vehicle 100 is transmitted from thevehicles 100 with a constant time cycle.

The driving characteristic storage unit 223 stores information of thedriving characteristics of the vehicle 100 stored in the drivingcharacteristic storage unit 153 of the vehicle 100 by vehicles on thebasis of the vehicle IDs included in the information transmitted fromthe vehicles 100. The driving characteristic storage unit 223 updatesthe stored information of the driving characteristics whenever theinformation of the driving characteristics of the vehicle 100 istransmitted from the vehicles 100 with a constant time cycle.

The center controller 210 stores the vehicle information input from theplural vehicles 100 as statistical information in a statistics database230. The statistics database 230 includes an average vehicle speedstorage unit 231, an average inter-vehicle distance storage unit 232,and an occurrence probability storage unit 233.

The average vehicle speed storage unit 231 collects information of theaverage vehicle speed of the vehicle 100 stored as a part of the drivingcharacteristics of the vehicle 100 in the driving characteristic storageunit 153 of the vehicle 100 from plural vehicles 100 and calculates theaverage value of the collected average vehicle speeds of the pluralvehicles 100 as statistical information.

The average inter-vehicle distance storage unit 232 collects informationof the average inter-vehicle distance of the vehicle 100 stored as apart of the driving characteristics of the vehicle 100 in the drivingcharacteristic storage unit 153 of the vehicle 100 from plural vehicles100 and calculates the average value of the collected averageinter-vehicle distances of the plural vehicles 100 as statisticalinformation.

The occurrence probability storage unit 233 collects information of theoccurrence probability of sudden lane change at the respective runningpositions stored as a part of the driving characteristics of the vehicle100 in the driving characteristic storage unit 153 of the vehicle 100from plural vehicles 100 and calculates the average value of thecollected occurrence probabilities of sudden lane change of the pluralvehicles 100 as statistical information for each running position of thevehicle 100. The occurrence probability storage unit 233 calculates theaverage value of the occurrence probabilities of sudden lane change ofthe vehicle 100 for each position individually corresponding to thelinks L (see FIG. 2) in the map information registered in the mapinformation database 212.

As illustrated in FIG. 2, the map information registered in the mapinformation database 212 includes node information that is informationon the nodes N indicating the positions on roads and link informationthat is information on links L. In this embodiment, the nodes N are setat plural positions spaced at constant intervals in the travelingdirection of the vehicle 100 for each traffic lane. The node informationincludes the position information of the nodes N or the road informationfor each traffic lane at the positions of the nodes N. The link L is setas a section defined by two nodes N between the two nodes N. The linkinformation includes the road information for each traffic lane in thesection of the link L. The road information includes informationindicating a running load when the vehicle 100 runs in the section ofthe link L, information indicating the type of the road, informationindicating the gradient of the road, or information indicating the widthand the road surface resistance of the traffic lane. The running load isdefined on the basis of movement time, movement speed, fuel consumption,power consumption, and the like.

In this case, a link L connecting two nodes N arranged in the travelingdirection of the vehicle 100 in the same traffic lane corresponds to thedirect advance of the vehicle 100. On the other hand, a link Lconnecting two nodes N arranged in the direction intersecting thetraveling direction of the vehicle in neighboring traffic lanescorresponds to the lane change of the vehicle 100.

In a place in which the lane change is inhibited by legal restrictions,a link L is not set to connect two nodes N arranged in the directionintersecting the traveling direction of the vehicle in the neighboringtraffic lanes. In the example illustrated in FIG. 2, in a constantsection located in front of a stop line of the vehicle 100 at a point ofintersection P, a link L is not set to connect two nodes N arranged inthe direction intersecting the traveling direction of the vehicle in theneighboring traffic lanes. In the example illustrated in FIG. 2, a linkL is not set to connect a node N located in the vicinity of a stop lineof the right lane set as a lane dedicated to the right turn in thesection through which the vehicle 100 passes before turning left at thepoint of intersection P and a node N of the lane in the section throughwhich the vehicle passes after turning left at the point of intersectionP.

As illustrated in FIG. 1, a cost calculating unit 240 as the predictedvalue calculating unit in the center controller 210 calculates a costCost of the link L which is the predicted value of the occurrenceprobability of sudden lane change in the link L set in the mapinformation on the basis of the information read from the statisticsdatabase 230 and the vehicle database 220.

Specifically, the cost calculating unit 240 calculates the cost Cost ofthe link L on the basis of Expression (1).

$\begin{matrix}{{cost} = {{Pa} + {\left( {{Pi} - {Pa}} \right) \times \frac{\log \left( {{Di} + 1} \right)}{\log \left( {{Dj} + 1} \right)}} + {K\; 1} + {K\; 2} + {K\; 3}}} & {{Expression}\mspace{14mu} (1)}\end{matrix}$

Here, Pa represents an average value of the occurrence probabilities ofsudden lane change of plural vehicles 100 in all the links L included inthe traveling route from the current point to the destination point andis calculated as an average value of the occurrence probabilities ofsudden lane change in all the links L stored in the occurrenceprobability storage unit 233 of the statistics database 230. Pirepresents an average value of the occurrence probabilities of suddenlane change of plural vehicles 100 in a target link L and is stored inthe occurrence probability storage unit 233 of the statistics database230. Di represents an information quantity of the statisticalinformation used to calculate Pi. In this embodiment, the number ofvehicles of which the statistical information is collected is defined asthe information quantity of the statistical information. Dj is definedas a value serving as the reference of the information quantity of thestatistical information when determining whether the value of Pi is usedas the predicted value of the occurrence probability of sudden lanechange in the target link L.

As illustrated in FIG. 3, the difference between the cost value Cost ofthe link L and the value of Pi decreases as the value of Di as theinformation quantity of the statistical information used to calculate Piincreases. This is because the larger the value of Di as the informationquantity of the statistical information becomes, the higher thereliability of Pi calculated using the statistical information becomes.

K1 represents a first addition value for weighting the predicted valueof the occurrence probability of sudden lane change in the link L inconsideration of whether the target link L is a link L corresponding tothe lane change of the vehicle 100 and satisfies a relational expressionof K1=α1×C.

Here, α1 is a coefficient indicating a degree of weighting based onwhether the target link L is the link L corresponding to the lane changeof the vehicle 100 at the time of calculating the cost Cost of the linkL. C varies depending on whether the target link L is a link Lcorresponding to the lane change of the vehicle 100. In this embodiment,C is set to 1 when the target link L is the link L corresponding to thelane change of the vehicle 100, and is set to 0 when the target link Lis the link L corresponding to the direct advance of the vehicle 100.Accordingly, the first addition value K1 that is added to the cost Costof the link L set by connecting two nodes N in the directionintersecting the traveling direction of the vehicle 100 is greater thanthe first addition value K1 that is added to the cost Cost of the link Lset by connecting two nodes N in the traveling direction of the vehicle100.

Weight is a correction coefficient for correcting the degree ofweighting of the first addition value K1 for the cost Cost and isexpressed by Expression (2).

$\begin{matrix}{{Weight} = e^{- \frac{L^{2}}{2\; \sigma^{2}}}} & {{Expression}\mspace{14mu} (2)}\end{matrix}$

L is a value indicating a distance from a specific point. σ is acoefficient for defining what the degree of weighting varies dependingon the value of L. Here, the specific point means a point at which thesteering operation frequency of the vehicle is greater than apredetermined threshold value.

As illustrated in FIG. 4, the value of weight gradually increases as thedistance from the specific point decreases. This is because since thedriver's burden when the sudden lane change of the vehicle 100 occurs isgreat at the time of performing the lane change of the vehicle 100 whileperforming the steering operation of the vehicle, it is necessary toincrease the weighting value of the first addition value K1 at the timeof calculating the cost Cost of the link L.

In this embodiment, a point of right and left turns, a point of a sharpcurve, a point of intersection, and a point at which the number oftraffic lanes decreases are set as the specific point. Information foridentifying these points is included in advance in the link informationof the map information registered in the map information database 212.

In this embodiment, a destination point of the traveling section storedin the section storage unit 221 of the vehicle database 220 is also setas the specific point. When the destination of the traveling section isset, information for identifying the destination point is added to thelink information of the map information registered in the mapinformation database 212.

In this embodiment, a point at which the steering operation isfrequently performed when the vehicle 100 actually runs is also set asthe specific point. This point is set on the condition that the steeringoperation frequency is greater than a predetermined threshold value whenthe steering operation frequency is stored as a part of the drivingcharacteristics of the vehicle 100 in the driving characteristic storageunit 223 of the vehicle database 220. Information for identifying thispoint is added to the link information of the map information registeredin the map information database 212.

K2 in Expression (1) is a second addition value for weighting thepredicted value of the occurrence probability of sudden lane change inthe link L in consideration of the appropriateness of personal drivingcharacteristics in the section corresponding to the link L and satisfiesa relational expression of K2=α2×(X1/X2).

Here, α2 is a coefficient indicating a degree of weighting of theappropriateness of personal driving characteristics in the sectioncorresponding to the link L at the time of calculating the cost Cost ofthe link L. In this embodiment, X1 represents the average value of theaverage vehicle speeds of plural vehicles 100 and is stored in theaverage vehicle speed storage unit 231 of the statistics database 230.On the other hand, X2 represents the value of the average vehicle speedof a guidance target vehicle 100 and is stored in the drivingcharacteristic storage unit 223 of the vehicle database 220.

Accordingly, when the average vehicle speed of plural vehicles 100 inthe section corresponding to the link L is high, the value of the secondaddition value K2 increases with the increase in the value of X1.However, when the average vehicle speed of the guidance target vehicle100 is also high, the increase of the second addition value K2 issuppressed with the increase in the value of X1 due to the increase inthe value of X2. That is, the appropriateness for a section in which theaverage vehicle speed of plural vehicles 100 is high is high when theaverage vehicle speed of the guidance target vehicle 100 is high.Accordingly, the second addition value K2 is set by considering that thedriver's burden decreases when the sudden lane change occurs in the samesection.

The average value of the average inter-vehicle distances of the guidancetarget vehicle 100 stored in the driving characteristic storage unit 223of the vehicle database 220 may be used as X1 and the average value ofthe average inter-vehicle distances of plural vehicles 100 stored in theaverage inter-vehicle distance storage unit 232 of the statisticsdatabase 230 may be used as X2. In this case, when the averageinter-vehicle distances of plural vehicles 100 in the sectioncorresponding to the link L is small, the value of the second additionvalue K2 increases with the decrease in the value of X2. However, whenthe average inter-vehicle distance of the guidance target vehicle 100 isalso small, the increase of the second addition value K2 is suppressedwith the decrease in the value of X2 due to the decrease in the value ofX1. That is, the appropriateness for a section in which the averageinter-vehicle distance of plural vehicles 100 is small is high when theaverage inter-vehicle distance of the guidance target vehicle 100 issmall. Accordingly, the second addition value K2 is set by consideringthat the driver's burden decreases when the sudden lane change occurs inthe same section.

K3 in Expression (1) is a third addition value for weighting thepredicted value of the occurrence probability of sudden lane change inthe link L in consideration of the appropriateness of the personalvehicle characteristics in the section corresponding to the link L andsatisfies a relational expression of K3=α3×(Y1/Y2).

Here, α3 is a coefficient indicating a degree of weighting of theappropriateness of the personal vehicle characteristics in the sectioncorresponding to the link L at the time of calculating the cost Cost ofthe link L. In this embodiment, Y1 represents the value of the vehiclewidth of the guidance target vehicle 100 and is stored in the vehiclecharacteristic storage unit 222 of the vehicle database 220. On theother hand, Y2 represents the value of the lane width of the sectioncorresponding to the link L and is included in the link information ofthe map information registered in the map information database 212.

Accordingly, when the lane width of the section corresponding to thelink L is small, the value of the third addition value K3 increases withthe decrease in the value of Y2. However, when the vehicle width of theguidance target vehicle 100 is small, the increase of the third additionvalue K3 is suppressed with the decrease in the value of Y2 due to thedecrease in the value of Y1. That is, the appropriateness for thesection in which the lane width is small is high when the vehicle widthof the guidance target vehicle 100 is small. Accordingly, the thirdaddition value K3 is set by considering that the driver's burdendecreases when the sudden lane change occurs in the same section.

The third addition value K3 may be set to satisfy a relationalexpression of K3=α3×(1/(Y1 a×Y2 a)), the value of the weight of theguidance target vehicle 100 stored in the vehicle characteristic storageunit 222 of the vehicle database 220 may be used as Y1 a, and the valueof the road surface resistance of the section corresponding to the linkL included in the link information of the map information registered inthe map information database 212 may be used as Y2 a. In this case, whenthe value of the road surface resistance of the section corresponding tothe link L is small, the value of the third addition value K3 increaseswith the decrease in the value of Y2 a. However, when the weight of theguidance target vehicle 100 is large, the increase of the third additionvalue K3 is suppressed with the decrease in the value of Y2 a due to theincrease in the value of Y1 a. That is, the appropriateness for thesection in which the value of the road surface resistance is small ishigh when the weight of the guidance target vehicle 100 is large.Accordingly, the third addition value K3 is set by considering that thedriver's burden decreases when the sudden lane change occurs in the samesection.

A recommended lane setting unit 241 of the center controller 210searches for a traveling route in which the total sum of the costs ofthe links L calculated by the cost calculating unit 240 is minimized inthe traveling sections stored in the section storage unit 221 using aDijkstra's algorithm or the like. The recommended lane setting unit 241sets a traffic lane located in the searched traveling route as arecommended lane and outputs information of the set recommended lane tothe center communication instrument 211. Accordingly, the information ofthe recommended lane set by the recommended lane setting unit 241 istransmitted from the center communication instrument 211 to the onboardcommunication instrument 123 by radio communications and is then inputfrom the onboard communication instrument 123 to the onboard controller150.

The process flow of the recommended lane guiding process that isperformed by the traffic lane guidance system for a vehicle according tothis embodiment will be described below in brief with reference to theflowchart illustrated in FIG. 5. As illustrated in FIG. 5, in step S10,the navigation system 131 sets a destination point on the basis of adriver's input operation and inputs the information of the travelingroute from the current point to the destination point to the onboardcontroller 150. Then, the section setting unit 151 of the onboardcontroller 150 sets the traveling route input from the navigation system131 as the traveling route of the vehicle 100.

Then, in step S11, the onboard controller 150 outputs the information ofthe traveling route of the vehicle set by the section setting unit 151to the onboard communication instrument 123. Then, the information ofthe traveling route of the vehicle 100 is transmitted from the onboardcommunication instrument 123 to the center communication instrument 211by radio communications is then input from the center communicationinstrument 211 to the center controller 210.

Subsequently, in step S12, the center controller 210 stores theinformation of the traveling route of the vehicle 100 input from thecenter communication instrument 211 in the section storage unit 221.Then, in step S13, the cost calculating unit 240 of the centercontroller 210 calculates the costs of links L included in the travelingroute of the vehicle 100 stored in the section storage unit 221 as apredicted value calculating step.

Subsequently, in step S14, the recommended lane setting unit 241 of thecenter controller 210 searches for a traveling route in which the totalsum of the costs of the links L calculated by the cost calculating unit240 is minimized using the Dijkstra's algorithm or the like. In theexample illustrated in FIG. 6, the traveling route R1 in which the totalsum of the costs of the links L is minimized is displayed by half-tonedot meshing. The recommended lane setting unit 241 sets a lane locatedin the searched traveling route R1 as the recommended lane.

Then, in step S15, the recommended lane setting unit 241 outputs theinformation of the set recommended lane to the center communicationinstrument 211. Then, the information of the recommended lane istransmitted from the center communication instrument 211 to the onboardcommunication instrument 123 by radio communications and is then inputfrom the onboard communication instrument 123 to the onboard controller150.

Subsequently, in step S16, the guidance information generating unit 154of the onboard controller 150 generates guidance information for urgingthe driver to run in the recommended lane on the basis of theinformation of the recommended lane input from the onboard communicationinstrument 123 as a guidance information generating step.

Then, in step S17, the guidance information generating unit 154 outputsthe generated guidance information to the HMI 132. As a result, the HMI132 gives an alarm for urging the driver to run in the recommended laneon the basis of the guidance information input from the guidanceinformation generating unit 154.

The operation of the traffic lane guidance system for a vehicleaccording to this embodiment will be described below. When the vehicle100 is guided to a recommended lane in which the vehicle 100 has to runin the traveling route from a current point to a destination point,first, the costs of the links L included in the traveling route arecalculated as the predicted values of the occurrence probability ofsudden lane change of the vehicle 100 in the links L. Then, a trafficlane located in the traveling route in which the total sum of the costsof the links L is minimized is set as a recommended lane in which thevehicle 100 is recommended to run in the traveling route from thecurrent point to the destination point. That is, the optimal trafficlane for suppressing the occurrence of sudden lane change of the vehicle100 is set as the recommended lane in consideration of the entire routefrom the current point to the destination point.

In this case, the cost of a link L is calculated using the statisticalinformation of the previous occurrence probabilities of sudden lanechange of plural vehicles 100 in the same link L. Accordingly, when theinformation quantity of the statistical information is small, thereliability of the cost value of the link L calculated using thestatistical information is not satisfactorily obtained. Therefore, it isdifficult to appropriately search for a recommended lane in which thevehicle 100 has to run in the traveling route from the current point tothe destination point on the basis of the calculated cost values of thelinks L.

Accordingly, in this embodiment, the calculated cost value of the link Lis corrected in consideration of the information quantity of thestatistical information used to calculate the cost of the link L. As aresult, it is possible to appropriately search for a recommended lane inwhich the vehicle 100 has to run in the traveling route from the currentpoint to the destination point on the basis of the corrected costvalues.

As described above, according to the first embodiment, the followingadvantages can be obtained. (1) The cost calculating unit 240 calculatesthe cost as the predicted value of the occurrence probability of suddenlane change when the vehicle 100 runs in the route from the currentpoint to the destination point for each section corresponding to thelinks L. The route in which the sudden lane change of the vehicle 100does not occur well is extracted from the route from the current pointto the destination point on the basis of the calculated costs and thetraffic lane included in the extracted route is set as the recommendedlane. That is, the recommended lane is set to a traffic lane in whichthe occurrence of the sudden lane change of the vehicle 100 can besuppressed in consideration of the entire route from the current pointto the destination point. Accordingly, by causing the guidanceinformation generating unit 154 to generate guidance information for theset recommended lane and to output the generated guidance information tothe HMI 132, it is possible to guide the vehicle to a traffic lane moresuitable for suppressing the occurrence of the sudden lane change of thevehicle 100.

(2) The recommended lane setting unit 241 sets the traffic lane includedin the route in which the total sum of the costs as the predicted valuesof the occurrence probability of sudden lane change is minimized in theroute from the current point to the destination point as the recommendedlane. Accordingly, the traffic lane included in the route in which thesudden lane change of the vehicle 100 occurs less in consideration ofthe entire route from the current point to the destination point is setas the recommended lane.

(3) The recommended lane setting unit 241 determines the traffic laneincluded in the route in which the total sum of the costs as thepredicted values of the occurrence probability of sudden lane change isminimized by applying a Dijkstra's algorithm to the cost as thepredicted value of the occurrence probability of sudden lane changecalculated for each link L included in the route from the current pointto the destination point. Accordingly, it is possible to easilyimplement a configuration for determining the route in which the totalsum of the costs as the predicted values of the occurrence probabilityof sudden lane change is minimized in the route from the current pointto the destination point.

(4) The weighting value of the first addition value K1 for the cost asthe predicted value of the occurrence probability of sudden lane changein a link L corresponding to the section in which the vehicle 100 runsat the time of changing the traffic lane is set to be greater than thatfor the predicted value in a link L corresponding to a section in whichthe vehicle 100 runs straightly in a traffic lane. That is, theweighting value is set for the costs as the predicted values of theoccurrence probability of sudden lane change depending on situations inconsideration of the variation of the driver's burden when the suddenlane change occurs depending on whether to change the lane. Accordingly,it is possible to guide the vehicle to a traffic lane more suitable forsuppressing the occurrence of the sudden lane change of the vehicle 100depending on the situations.

(5) As the running position of the vehicle 100 becomes closer to thepoint of intersection P, the weighting value of the first addition valueK1 for the cost as the predicted value of the occurrence probability ofsudden lane change in the link L corresponding to the section in whichthe vehicle 100 runs at the time of changing the traffic lane is set tobe greater. That is, the weighting value for the cost as the predictedvalue of the occurrence probability of sudden lane change is changeddepending on the situations in consideration of the variation of thedriver's burden when the sudden lane change occurs due to the variationin the distance from the point of intersection P. Accordingly, it ispossible to guide the vehicle to a traffic lane more suitable forsuppressing the occurrence of the sudden lane change of the vehicle at apoint of intersection P or the like depending on the situation.

(6) The weighting value for the cost as the predicted value of theoccurrence probability of sudden lane change is changed depending on thesituations by changing the weighting value of the second addition valueK2 for the cost as the predicted value of the occurrence probability ofsudden lane change in the link L in consideration of the variation ofthe driver's burden when the sudden lane change occurs due to theappropriateness of the personal driving characteristics for the sectioncorresponding to the link L. Accordingly, it is possible to guide thevehicle to a traffic lane more suitable for suppressing the occurrenceof the sudden lane change of the vehicle 100 depending on the personaldriving characteristics.

(7) The weighting value for the predicted value of the occurrenceprobability of sudden lane change is changed depending on the situationsby changing the weighting value of the third addition value K3 for thecost as the predicted value of the occurrence probability of sudden lanechange in the link L in consideration of the variation of the driver'sburden when the sudden lane change occurs due to the appropriateness ofthe vehicle characteristics for the section corresponding to the link L.Accordingly, it is possible to guide the vehicle to a traffic lane moresuitable for suppressing the occurrence of the sudden lane change of thevehicle depending on the situation.

(8) The nodes N include plural positions spaced in the travelingdirection of the vehicle 100 in the traffic lanes of the route portionbetween neighboring points of intersection P in the route from thecurrent point to the destination point. Accordingly, since more nodes Nthan the nodes N when the nodes N are set at only the positionscorresponding to the points of intersection P in the route are set inthe route, it is possible to guide the vehicle to a traffic lane moresuitable for suppressing the occurrence of the sudden lane change of thevehicle 100 in more detail.

Second Embodiment

A second embodiment of a traffic lane guidance system for a vehicle anda traffic lane guidance method for a vehicle will be described belowwith reference to the accompanying drawings. The second embodiment isdifferent from the first embodiment, in the aspect of setting arecommended lane based on the costs of links L. Accordingly, in thefollowing description, a configuration different from that of the firstembodiment will be mainly described and description of the configurationidentical or corresponding to that of the first embodiment will not berepeated.

In this embodiment, the recommended lane setting unit 241 reads thecalculated cost value of a link L connecting a node N corresponding to adestination point of the traveling route stored in the section storageunit 221 and a node N adjacent to the node N in the traveling directionof the vehicle 100.

Then, the recommended lane setting unit 241 determines whether the readcalculated cost value of the link L is greater than a predeterminedthreshold value. The recommended lane setting unit 241 sets a sectioncorresponding to the link L as the recommended lane when it isdetermined that the read calculated cost value of the link L is notgreater than the predetermined threshold value.

On the other hand, when it is determined that the read calculated costvalue of the link L is greater than the predetermined threshold value,the recommended lane setting unit 241 reads the calculated cost value ofa link L connecting the node N corresponding to the destination pointand a node N adjacent to the node N in the direction intersecting thetraveling direction of the vehicle 100. Then, the recommended lanesetting unit 241 sets a section corresponding to the link L as therecommended lane on the condition that the read calculated cost value ofthe link L is not greater than the predetermined threshold value. Whenthe read calculated cost value of the link L is greater than thepredetermined threshold value, the recommended lane setting unit 241determines that a traveling route capable of avoiding a local increasein the occurrence probability of sudden lane change is not present inthe traveling route stored in the section storage unit 221 and ends thesetting of the recommended lane.

Thereafter, the recommended lane setting unit 241 repeatedly performsthe above-mentioned process from the destination point side to thecurrent point side of the traveling sections stored in the sectionstorage unit 221. When the above-mentioned process is performed up tothe node N corresponding to the current point, the traveling route inwhich the number of links L set by connecting two nodes N in thedirection intersecting the traveling direction of the vehicle 100 isminimized is extracted from the sections stored in the section storageunit 221 on the condition that the link L in which the cost is greaterthan a predetermined threshold value is not included. That is, thetraveling route in which the lane change frequency of the vehicle 100 isminimized while avoiding the occurrence probability of sudden lanechange locally increases is extracted from the sections stored in thesection storage unit 221. A traffic lane located in the extractedtraveling route is set as the recommended lane.

In the example illustrated in FIG. 7, when “0.5” is set as thepredetermined threshold value, the calculated cost value of thedetermination target link L is set to “0.3” in the section through whichthe vehicle 100 passes after turning left at the point of intersectionP. Accordingly, in this section, a traffic lane located in the travelingroute R2 in which the vehicle runs straightly in the left lane is set asthe recommended lane. On the other hand, in the example illustrated inFIG. 7, the calculated cost value of some links L of the determinationtarget links L is set to “0.6” in the section through which the vehicle100 passes before turning left at the point of intersection P.Accordingly, in this section, a traffic lane located in the travelingroute R2 in which the vehicle runs straightly in the right lane andchanges the traffic lane to the left lane in the way is set as therecommended lane.

According to the second embodiment, the following advantage can beobtained in addition to the advantages of (1) and (4) to (8) of thefirst embodiment. (9) On the premise that a section in which the suddenlane change of the vehicle 100 often occurs is not locally included, atraffic lane included in the route in which the lane change frequency isminimized in the route from the current point to the destination pointis set as the recommended lane. That is, since the recommended lane doesnot locally include a section in which the sudden lane change of thevehicle 100 often occurs and the lane change frequency is minimized, itis possible to guide the vehicle to a traffic lane still more suitablefor suppressing the occurrence of the sudden lane change of the vehicle100.

The above-mentioned embodiments may be embodied in the followingconfigurations. In the above-mentioned embodiments, the nodes N in themap information registered in the map information database 212 may beset as positions of specific traffic elements such as points ofintersection, traffic lights, and curves or points at which the numberof traffic lanes is changed on a road.

In the above-mentioned embodiments, the cost calculating unit 240 mayadd an addition value for weighting the predicted value of theoccurrence probability of sudden lane change in a link L inconsideration of occurrence of sudden braking in the sectioncorresponding to the link L at the time of calculating the cost Cost ofthe link L. In this case, a relational expression of (additionvalue)=(weighting coefficient)×(occurrence probability of suddenbraking) is satisfied. Accordingly, when the occurrence probability ofsudden braking in the section corresponding to the link L increases, theaddition value also increases. This is because the driver's burden whenthe sudden lane change occurs in the same section is considered toincrease when the occurrence probability of sudden braking in thesection corresponding to the link L is high.

In the above-mentioned embodiments, the cost calculating unit 240 mayadd an addition value for weighting the predicted value of theoccurrence probability of sudden lane change in a link L inconsideration of occurrence of passing in the section corresponding tothe link L at the time of calculating the cost Cost of the link L. Inthis case, a relational expression of (addition value)=(weightingcoefficient)×(occurrence probability of passing) is satisfied.Accordingly, when the occurrence probability of passing in the sectioncorresponding to the link L increases, the addition value alsoincreases. This is because the driver's burden when the sudden lanechange occurs in the same section is considered to increase when theoccurrence probability of passing in the section corresponding to thelink L is high.

In the above-mentioned embodiments, the cost calculating unit 240 mayadd an addition value for weighting the predicted value of theoccurrence probability of sudden lane change in a link L inconsideration of occurrence of right turn waiting of a preceding vehiclein the section corresponding to the link L at the time of calculatingthe cost Cost of the link L. In this case, a relational expression of(addition value)=(weighting coefficient)×(occurrence probability ofright turn waiting of a preceding vehicle) is satisfied. Accordingly,when the occurrence probability of right turn waiting of a precedingvehicle in the section corresponding to the link L increases, theaddition value also increases. This is because the driver's burden whenthe sudden lane change occurs in the same section is considered toincrease when the occurrence probability of right turn waiting of apreceding vehicle in the section corresponding to the link L is high.

In the above-mentioned embodiments, the cost calculating unit 240 mayadd an addition value for weighting the predicted value of theoccurrence probability of sudden lane change in a link L inconsideration of occurrence of stopping and going in the sectioncorresponding to the link L at the time of calculating the cost Cost ofthe link L. In this case, a relational expression of (additionvalue)=(weighting coefficient)×(occurrence probability of stopping andgoing) is satisfied. Accordingly, when the occurrence probability ofstopping and going in the section corresponding to the link L increases,the addition value also increases. This is because the driver's burdenwhen the sudden lane change occurs in the same section is considered toincrease when the occurrence probability of stopping and going in thesection corresponding to the link L is high.

In the above-mentioned embodiments, the cost calculating unit 240 mayadd an addition value for weighting the predicted value of theoccurrence probability of sudden lane change in a link L correspondingto the direct advance in the left lane or the lane change to the leftlane in consideration of the street parking frequency at the time ofcalculating the cost Cost of the link L. In this case, a relationalexpression of (addition value)=(weighting coefficient)×(street parkingfrequency of section/personal taste for left lane) is satisfied.Accordingly, the addition value increases when the street parkingfrequency in the section corresponding to the link L is large, but theincrease of the addition value is suppressed when the driver of theguidance target vehicle 100 has particular taste for the left lane. Thatis, the appropriateness for the section in which the street parkingfrequency is large is high when the driver of the guidance targetvehicle 100 has particular taste for the left lane. Accordingly, theaddition value is set in consideration that the driver's burden when thesudden lane change occurs in the same section decreases.

In the above-mentioned embodiments, the cost calculating unit 240 mayconsider whether a guide rail is present in the section corresponding toa link L corresponding to the direct advance in the left lane or thelane change to the left lane at the time of calculating the cost Cost ofthe link L. In this case, when a guide rail is present in the sectioncorresponding to the link L, the cost value Cost in the sectioncorresponding to the same link L is set to be smaller than that when theguide rail is not present.

In the above-mentioned embodiments, the cost calculating unit 240 mayconsider whether a median is present in the section corresponding to alink L corresponding to the direct advance in the right lane or the lanechange to the right lane at the time of calculating the cost Cost of thelink L. In this case, when a median is present in the sectioncorresponding to the link L, the cost value Cost in the sectioncorresponding to the same link L is set to be smaller than that when themedian is not present.

In the above-mentioned embodiments, the cost calculating unit 240 mayconsider the presence or width of a road shoulder or a roadside zone inthe section corresponding to a link L corresponding to the directadvance in the left lane or the lane change to the left lane at the timeof calculating the cost Cost of the link L. In this case, when a roadshoulder or a roadside zone is present in the section corresponding tothe link L, the cost value Cost in the section corresponding to the samelink L is set to be smaller than that when the road shoulder or theroadside zone is not present. When the width of a road shoulder or aroadside zone is large in the section corresponding to the link L, thecost value Cost in the section corresponding to the same link L is setto be smaller that when the width of a road shoulder or a roadside zoneis small.

In the above-mentioned embodiments, the control center 200 may classifyinformation groups of elements into specific driving characteristicinformation groups by performing cluster analysis on information of theelements of the driving characteristics of the vehicles 100 stored inthe driving characteristic storage unit 223 of the vehicle database 220.In addition, the control center 200 may classify information groups ofelements into specific lane characteristic information groups byperforming cluster analysis on information of the elements of the lanecharacteristics in the map information registered in the map informationdatabase 212. In this case, at the time of calculating the cost valueCost of the link L, the cost calculating unit 240 sets the secondaddition value to be added to the predicted value of the occurrenceprobability of sudden lane change when the appropriateness of theclassified driving characteristic information groups and lanecharacteristic information groups is relatively high to be smaller thanthat when the appropriateness is relatively low.

In the above-mentioned embodiments, the control center 200 may storeinformation on the steering operation frequency when the vehicle 100actually runs in the statistics database 230 and may add information foridentifying the corresponding point as a specific point to the linkinformation of the map information registered in the map informationdatabase 212 on the condition that the average value of the frequenciesis greater than a predetermined threshold value.

In the above-mentioned embodiments, the control center 200 may detectwhether the steering operation in the vehicle 100 is performed byreceiving an image signal of the vehicle 100 imaged with the camerainstalled in the optical beacon road machine B from the optical beaconroad machine B and analyzing the image signal, and may acquire thesteering operation frequency in the vehicle 100 in each traffic lane onthe basis of the analysis result. On the condition that the frequency isgreater than a predetermined threshold value, the control center 200 mayadd information for identifying the corresponding point as a specificpoint at which the steering operation in the vehicle 100 is frequentlyperformed to the link information of the map information registered inthe map information database 212. In this case, the control center 200stores information on the steering operation frequency when the vehicle100 actually runs in the statistics database 230 and adds informationfor identifying the corresponding point as a specific point to the linkinformation of the map information registered in the map informationdatabase 212 on the condition that the average value of the frequenciesis greater than a predetermined threshold value.

In the first embodiment, the recommended lane setting unit 241 mayexclude a link L in which the cost calculated by the cost calculatingunit 240 is greater than a predetermined threshold value in thetraveling sections set by the section setting unit 151 and then maysearch for a traveling route in which the total sum of the costs of thelinks L calculated by the cost calculating unit 240 is minimized using aDijkstra's algorithm or the like. In this case, the recommended lanesetting unit 241 sets a traffic lane included in the traveling route inwhich the total sum of the costs is minimized as the recommended lane inthe traveling sections set by the section setting unit 151 on thecondition that the link L in which the cost Cost is greater than apredetermined threshold value is not included. In this configuration, aroute locally including a section in which the sudden lane change of thevehicle 100 often occurs in the route from the current point to thedestination point from the appropriate route candidates. That is, sincethe recommended lane does not locally include a section in which thesudden lane change of the vehicle 100 often occurs, it becomes easy toguide a vehicle 100 to a traffic lane more suitable for suppressing theoccurrence of sudden lane change of the vehicle 100.

In the above-mentioned embodiments, the costs in the sections from thecurrent point to the destination point may be calculated by the vehicle100. For example, first, information of the route from the current pointto the destination point is transmitted from the vehicle 100 to thecontrol center 200. Then, the control center 200 transmits informationof the costs of all the links L included in the corresponding route tothe vehicle 100. Then, the vehicle 100 specifies a recommended lane onthe basis of the transmitted information of the costs and generatesguidance information for urging the driver to run in the recommendedlane.

1. A traffic lane guidance system for a vehicle for guiding a driver ofthe vehicle to a recommended lane in which the vehicle is recommended torun from among traffic lanes included in a route from a current point ofthe vehicle as a first point to a destination point of the vehicle as asecond point, comprising: a vehicle component mounted on the vehicle tooutput guidance information for the driver; and a processor configuredto: calculate a predicted value indicating an occurrence probability ofsudden lane change in the traffic lanes on the basis of statisticalinformation acquired from a plurality of vehicles and an informationquantity of the statistical information; set an addition value, whereinthe addition value in the traffic lanes in a direction intersecting thetraveling direction of the vehicle is greater than the addition value inthe traffic lanes along the traveling direction; set a recommended laneon the basis of a sum of the predicted value and the addition value; andoutput guidance information via the vehicle component to the driveraccording to the recommended lane.
 2. The traffic lane guidance systemfor a vehicle according to claim 1, wherein the vehicle component is ahuman machine interface.
 3. The traffic lane guidance system for avehicle according to claim 2, wherein the human machine interface is oneof a display and a speaker.
 4. The traffic lane guidance system for avehicle according to claim 2, wherein the processor is furtherconfigured to include a traffic lane included in the route in which thetotal sum of the predicted values of the occurrence probability ofsudden lane change is minimized by applying a Dijkstra's algorithm tothe predicted value of the occurrence probability of sudden lane changecalculated for each traffic lane included in the route from the firstpoint to the second point.
 5. The traffic lane guidance system for avehicle according to claim 1, wherein the processor is furtherconfigured to set, as the recommended lane, the traffic lane included inthe route in which the sudden lane change of the vehicle occurs less inconsideration of the entire route from the first point to the secondpoint.
 6. The traffic lane guidance system for a vehicle according toclaim 1, wherein the processor is further configured to set a weightingvalue for the addition value and gradually increases the weighting valueset for the addition value as a distance from a point, at which asteering operation frequency of the vehicle is greater than apredetermined threshold value, decreases in the route from the firstpoint to the second point.
 7. The traffic lane guidance system for avehicle according to claim 1, wherein the processor is furtherconfigured to determine a second addition value which is different froma first addition value as the addition value to be added to thepredicted values of the occurrence probability of sudden lane changewhen the addition value is the first addition value and sets the secondaddition value, when an appropriateness of personal drivingcharacteristics for the traffic lanes is relatively high, to be smallerthan that when the appropriateness is relatively low, and wherein therecommended lane is set on the basis of the predicted values of theoccurrence probability of sudden lane change to which the first additionvalue and the second addition value are added.
 8. The traffic laneguidance system for a vehicle according to claim 7, wherein theprocessor is further configured to classify information acquired fromthe plurality of vehicles as information of elements of personal drivingcharacteristics into a plurality of driving characteristic informationgroups, classify information of elements of lane characteristics into aplurality of lane characteristic information groups, and set the secondaddition value to be added to the predicted values of the occurrenceprobability of sudden lane change, when an appropriateness of thedriving characteristic information groups and the lane characteristicinformation groups is relatively high, to be smaller than that when theappropriateness is relatively low.
 9. The traffic lane guidance systemfor a vehicle according to claim 7, wherein the processor is furtherconfigured to determine a third addition value which is different fromthe first addition value and the second addition value as the additionvalue to be added to the predicted values of the occurrence probabilityof sudden lane change and sets the third addition value, when anappropriateness of vehicle characteristics for the traffic lanes isrelatively high, to be smaller than that when the appropriateness isrelatively low, and wherein the processor sets the recommended lane onthe basis of the predicted values of the occurrence probability ofsudden lane change to which the first addition value, the secondaddition value, and the third addition value are added.
 10. The trafficlane guidance system for a vehicle according to claim 1, wherein thetraffic lanes include a plurality of positions spaced in the travelingdirection of the vehicle in the traffic lanes of a route portion betweenneighboring points of intersection in the route from the first point tothe second point.
 11. A traffic lane guidance method for a vehicle ofguiding a driver of the vehicle to a recommended lane in which thevehicle is recommended to run from among traffic lanes included in aroute from a current point of the vehicle as a first point to adestination point of the vehicle as a second point through the use of avehicle component mounted on the vehicle to output guidance informationfor the driver and a processor, the method comprising: calculating,using the processor, a predicted value indicating an occurrenceprobability of sudden lane change in the traffic lanes on the basis ofstatistical information acquired from a plurality of vehicles and aninformation quantity of the statistical information; calculating anaddition value in the traffic lanes, the addition value being greater ina direction intersecting the traveling direction of the vehicle than theaddition value in the traffic lanes along the traveling direction;setting a recommended lane on the basis of a sum of the calculatedpredicted value and the addition value; and outputting guidanceinformation via the vehicle component to the driver according to therecommended lane.